HIV is the leading cause of death in Africa, but only a small portion of the population is aware of their serostatus. Early diagnosis of HIV is essential for treatment of infected individuals as well as for prevention of future infections. HIV testing strategies change the prospects for infected individuals, and shape the course of the epidemic by improving survival of treated individuals and possibly changing HIV risk behaviors. As a result, the World Health Organization recently recommended opt-out testing in highly endemic regions, given the appropriate environment. The proposed research plan will evaluate the relationship between testing and risk behaviors, the epidemiologic implications of different testing strategies, and the cost- effectiveness in sub-Saharan Africa. The revised submission includes a broader geographical focus, additional training activities, stronger institutional support, and a narrowed scope for 2 aims. The project has the following specific aims: 1. Review the evidence on the relationship between HIV counseling and testing and risk behaviors related to sexual transmission of HIV in sub-Saharan Africa; 2. Assess how different testing strategies affect HIV epidemic outcomes in sub-Saharan Africa including prevalence, incidence, infections averted, and HIV-related deaths; 3. Evaluate the effectiveness and cost-effectiveness of different HIV testing strategies in sub- Saharan Africa; 4. Understand how policy makers use models and explore the ways in which models of HIV testing can provide useful inputs to the policy making process. I will evaluate the following HIV testing strategies: voluntary counseling and testing (VCT), scaled up VCT, provider-initiated counseling and testing, provider-initiated testing with limited counseling, and population-based screening. I will evaluate all strategies with limited and full availability of antiretroviral therapy. I am mentored by the PI and co-PI of experienced NIH-funded investigators with 15+ years of experience with HIV policy modeling. It is a product of my personal research objectives and training in infectious disease modeling, cost-effectiveness analysis, and global health. Support for this project will promote informed public health decisions for HIV testing in highly endemic regions, and will prepare me for a research career evaluating HIV treatment and prevention interventions.